RNA decay pathways are induced by TMV proteins impairing gene silencing as part of counter-defense strategy

GABRIELA CONTI; ANDREA LAURA VENTURUZZI; MARIA CECILIA RODRIGUEZ; MARTIN CRESPI; SEBASTIAN ASURMENDI

Foz de Iguazú

Congreso; International Plant Molecular Biology 2015; 2015

y International Society for Plant Molecular Biology

RNA decay pathways comprise a combination of mechanisms implicated in gene expression regulation, development and defense responses across all eukaryotes. In yeast and animal virus infections, viral transcripts must evade RNA decay mechanisms. Therefore, impairing RNA decay maybe a strategy employed by viruses and could be an additional cause for the generation of disease symptoms. In plants, it was demonstrated that RNA decay and Post-Transcriptional Gene Silencing (PTGS) are closely related and both mechanisms work antagonistically. However, there are no clear evidences for the role of RNA decay pathways on plant-virus interactions. Here, we show that tobacco plants infected with Tobacco Mosaic Virus and transgenic lines expressing TMV proteins with no silencing suppression activity increase the transcriptional levels of several RNA decay and PTGS transcripts. We observed alterations in RNA granules accumulation (p-bodies and si-bodies), increased rates of transgene induced RNA decay that resulted in a strong antagonistic effect on transgene PTGS amplification. We also demonstrated that RRP41 or RRP43 RNA exosome components knock-down by means of Virus-Induced Gene Silencing, produced developmental defects, changes in some miRNA transcripts and lower levels of TMV accumulation accompanied by milder symptoms. Thus, we propose that induction of RNA decay pathways could be a TMV counter-defense strategy to impair PTGS amplification and may also be implicated in the development of symptoms.